Computer screen with an icon



FIG. 1 is a front perspective view of an icon for a computer screen comprising the present invention, the broken line drawing of a computer screen is for illustrative purposes only and forms no part of the claimed design; and,

FIG. 2 is a front view thereof, on an enlarged scale the broken line drawing of a computer screen is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a icon for a computer screen, as shown and described. 